This invention relates generally to a labeling apparatus and method for applying labels to containers, and more particularly to a labeling apparatus and method employing a UV curable pressure sensitive adhesive for adhering a label to a container. Preferably this invention relates to the application of cut and stack labels, both opaque and transparent, to a container through a UV pressure sensitive curable adhesive.
The UV curable pressure sensitive adhesives used in this invention become tacky, or pressure sensitive, upon exposure to UV radiation.
A number of prior art systems exist for applying labels to containers. These systems employ either continuous roll fed labels or cut and stack labels.
Prior art labeling apparatus and methods employing labels in continuous roll form include label cutting and registration means for severing discrete labels from the roll and then registering them for attachment to the containers through a transfer vacuum drive system. In these prior art systems a hot melt adhesive generally is employed; being applied to both the leading and trailing edge of the back side of the labels for permitting attachment of the labels to the containers.
Although the above-described system is being commercially utilized, it does include a number of drawbacks for various applications. First, continuous roll fed labeling devices require both label cutting and registration units, which increase the complexity of the system. Second, hot melt adhesives are, at best, generally cloudy or milky in appearance and therefore are not effectively utilized to apply clear or transparent labels in a uniform fashion to clear containers. The uniform attachment of clear or transparent labels to clear containers, e.g., clear glass or plastic beer and soda bottles, is very desirable, providing a very clean finish, and also permitting the product inside of the bottle to be clearly and easily viewed through the label.
A further deficiency in connection with the use of hot melt adhesives is that high temperatures generally are required to apply the labels to the containers. The application of high temperatures to the containers often is undesired.
It is known to employ continuous rolls of transparent pressure sensitive labels for application to clear containers. However, as discussed above, the use of these continuous rolls require cutting and registration units that increase the complexity of the system. Moreover, the rolls of pressure sensitive labels often include a release liner covering the adhesive surface, thereby necessitating the removal of the release liner from the label during the continuous process. This also introduces an undesired complexity into the system.
It also is known to apply cut and stack labels (i.e., labels that have been cut off line and are retained in a stack within a dispensing magazine) to containers, such as bottles, in a continuous label application system. In accordance with this prior art system, a cold glue adhesive, which is water soluble, is applied to a glue transfer pad by a rubber transfer roll, and the glue transfer pad is moved into contact with the lower label of the stack to both apply glue to that label and remove the label from the stack onto the pad through surface adhesion with the adhesive. Thereafter, the label, with the cold glue thereon, is moved to a transfer drum, from where it is then applied to a container, such as a glass bottle. These cold glue adhesives generally have been utilized only in connection with paper labels that are capable of absorbing the moisture from the water soluble adhesives. In other words, systems employing water soluble cold glue adhesives are not well suited for use with non-porous, plastic labels.
Based on the deficiencies of the existing prior art systems, a need exists for a labeling apparatus and method that is not required to handle a tacky adhesive throughout the label handling and applying operations, and that is effective for use with plastic labels, preferably transparent plastic labels, for adhering such labels to containers; preferably clear glass bottles such as beer or soda bottles. Most preferably a need exists for the aforementioned type of system that does not require the use of label cutting and registration units of the type generally employed in labeling apparatus and methods that handle continuous roll fed labels; although, in accordance with the broadest aspects of this invention, the process can be employed with continuous roll fed label stock.
It is a general object of this invention to provide a method and apparatus for applying labels to containers that are reliable in operation.
It is a further object of this invention to provide a method and apparatus for applying labels devoid of any release liner to containers in a reliable manner.
It is a further object of the most preferred embodiment of this invention to provide a method and apparatus for applying transparent labels to clear containers in a reliable manner.
It is a further object of the most preferred embodiment of this invention to provide a method and apparatus for applying labels to containers that do not require the use of label cutting and registration devices of the type included in labeling systems that handle labels in continuous roll form.
It is still a further object of this invention to provide a method and apparatus for applying a label to a container wherein a tacky adhesive is not required to be handled throughout the entire label forming and applying operations.
The above and other objects of this invention are achieved in a UV labeling apparatus and method wherein a UV curable adhesive, which is non-tacky, is applied to the surface of a label to be attached to a bottle, and the label, with the UV curable adhesive thereon, is then sequentially fed through a UV cure operation to render the adhesive tacky and then to a station for immediately applying the label to a surface of the container through the tacky adhesive on the label.
In accordance with the most preferred embodiment of this invention, the labels are individual, cut and stack labels retained in a magazine, and the UV curable adhesive is applied to a lower surface of each label in the stack through a rotating transfer pad that moves sequentially through an adhesive application station in which a measured quantity of UV adhesive is transferred to the exposed surface of the pad, and then to a transfer station where the exposed surface of the pad with the adhesive thereon engages a lower surface of the lowermost label in the stack to both apply the adhesive to that label and remove the label from the stack through the surface adhesion created by the UV liquid.
In the most preferred embodiment of this invention, the individual labels carried on the transfer pads are then directed to a transfer assembly, wherein the individual labels are released from the pads and directed by the transfer assembly through a UV cure station in which the UV adhesive is rendered tacky, and then into a label application station for transferring the individual labels, with the tacky adhesive thereon, to the outer surface of a container, preferably a glass container, such as a beer or soda bottle.